Tag: sip

Introduction I have recently had a strange issue with call transfers on CME 12.0. I was getting “SIP/2.0 488 Not Acceptable Here” from ISP while trying to transfer a call from PSTN to another extension. Let’s see how we can solve this problem and make the transfer work. Equipment Used The phone I used was

Introduction In this post we will learn how to upload SIP firmware to Cisco 7911 IP Phone. This will make possible using the phone with third party SIP servers. The instruction below applies to all Cisco 7900 series IP phones. Step 1. Download the SIP firmware. Before we start, let’s download the required SIP firmware

Introduction In this article we will see how we can bypass SIP traffic blocking. There are a lot of countries where local ISPs block SIP traffic. It makes it impossible for enterprises or private persons to leverage from low rates on international calls provided by various SIP trunk providers. Solution One of the solutions is